The busy tourist area was cordoned off by police as paramedics treated the woman after the collision at 4.50pm on Tuesday.
A Scotland Yard spokesman said: “Police were called to reports of a female pedestrian in collision with a cyclist in Oxford Street, junction with Regents Street, W1.
“Officers and London Ambulance Service attended and the female was taken to hospital for treatment; her condition is not life threatening.
“Road closures were put in place while the scene was dealt with.”
The cyclist has not been arrested.
Buses were put on diversion after the collision.